1. Field of the Invention
Embodiments of the present invention generally relate to a spray dried catalyst slurry. More particularly, embodiments of the present invention relate to a spray died catalyst slurry for gas phase olefin polymerization.
2. Description of the Related Art
A number of methodologies used for delivering catalysts to reactors require the catalyst to be supported on an inert carrier such as silica. Impregnating a catalyst on a support has often been found to cause a significant decrease in catalyst activity. In addition, large particles (>25 micrometers) of the support material have frequently been found in the finished polymer product. These particles may adversely affect polymer properties. This has been observed in film applications where unexploded silica particles appear as defects or gels.
Spray-drying techniques have been employed as an alternative to supported particles. Once a catalyst has been spray dried, the spray dried catalyst is added to a diluent to form a catalyst slurry and pumped to a polymerization reactor. A high solids concentration within the catalyst slurry is desirable to reduce the amount of slurry. A reduction in the amount of slurry reduces transportation expenses. A reduction in the amount of slurry also reduces the amount of diluent that must be ultimately isolated and either discarded or recycled. This separation process is timely and can greatly increase capital cost.
However, a high solids concentration typically increases the slurry viscosity. A high solids concentration also increases the amount of foaming which is typically generated by cooling gas during formation of the spray dried catalysts. A high slurry viscosity and foaming often cause handling problems, storage problems as well as reactor injection problems.
There is a need, therefore, for a spray dried catalyst slurry that has an increased solids content, a low viscosity, and a limited amount of foam.